Field of the Invention
The present invention relates to soda recovery boilers as are used by the wood pulping industry. In particular, the invention is directed to shatter steam sprays for dispersing flow streams of smelt emerging from the boiler bed.
Description of the Prior Art
Pursuant to present-day paper pulp mill operations, raw wood is delignified by a thermo-chemical process comprising an approximately 350.degree. F. cook in the presence of sodium hydroxide, sodium carbonate, sodium sulfide and other sodium based compounds. Under such conditions, the lignin binder in the raw wood matrix which holds the natural cellulose fibers together reacts with the sodium compounds to form water soluble lignin-sodium complexes thereby permitting a water wash separation of the black, tar-like lignin from the fiber for manufacture of paper.
Although the sodium compounds used in the aforedescribed process are relatively inexpensive, the quantities consumed in the production of an average pulp mill necessitate an economical recovery and re-cycle of the chemical values. Moreover, such sodium-lignin complexes contain sufficient heat value and volatility to contribute favorably to the overall mill heat balance. These characteristics are combined in the liquor recovery furnace by fueling a boiler furnace with a concentrated flow stream of the spent or black pulping liquor. Combustion of the lignin fraction generates sufficient heat to evaporate the residual water vehicle and heat the steam required for the primary evaporative liquor concentration process. Residual ash, predominately sodium carbonate, falls to the furnace bed as a viscous smelt. Such smelt is cooled and dissolved in water to form the green liquor makeup stream from which the other fresh cooking liquor compounds are made.
In transition from the furnace bed to a green liquor dissolving tank, smelt flows in thin streams from numerous spouts around the furnace bed perimeter. Such smelt streams fall directly into the dissolving tank. To prevent or minimize violent chemical reactions as the sodium laden smelt combines with the aqueous green liquor, the smelt spout streams are shattered by dispersion jets of steam.
Traditionally, these shattering sprays have been rigidly secured to the furnace frame or foundation structures in such ways as to survive the extremely hot and chemically hostile conditions. Moreover, dispersion of the smelt streams notwithstanding, an irregular, low amplitude vibration continuously shakes the structure due to the sodium-water reactions.
Although the shatter sprays are rigidly mounted for survivability in a hostile environment, such rigid mounting is, in many respects, self defeating. When the spray is secured, it must be aimed at a compromise location based on the normal or average smelt flow rate. However, this smelt flow rate is unpredictably variable over a wide range. Hence, for any particular shatter spray, the fixed positionment is only occasionally correct, at best. The result is that a considerably higher level of reaction vibration occurs than is necessary.
An object of the present invention, therefore, is provision of a shatter spray mount that is adjustable.
Another object of the present invention is an adjustable shatter spray mount that will survive the hostile operating conditions.
Another object of the present invention is an articulating shatter spray mount that remains functional after months of operation in a hostile environment.